Mercury light



l Snventor -Y @han Gttornegs W. S. BRIAN MERCURY LIGHT Filed Dec. 4, 1941 July 14, 1942.

Patented July 14, 1942 MERCURY LIGHT William S. Brian, Owensboro, Ky., assignor to vGeneral Motors Corporation, Detroit, Mich., al corporationvof Delaware Application December 4, 1941, Serial No. 421,587 A 9 Claims. (Cl. 176-13) This invention relates to means for producing ultraviolet light rays and more particularly to mercury Atubes operated by low voltage for said ultraviolet production. y

There are many instances in which it is desired to produce ultraviolet light rays for various uses and it .has been believed necessary to apply high voltages to a conned body of mercury in order to obtain said rays in suilicient quantity to be useful. This usually necessitated theuse of large sources ofV power and transiormers and expensive installations. These were 'in most cases bulky and heavy and not readily at any great distance and almost no vertical distance so that occupants of planes'would be unable to see them.

It is therefore an object of my invention to provide a readily portable source ci ultraviolet light.

It is a further object of my invention to provide 'a' source of ultravioletlight which will operate from a low voltage source.

It is a still further object oi my invention to provide a mercury tube source of ultraviolet rays which is inexpensive, efficient, will operate from low voltage and have long life.

With the above and other .objects in view, which will become apparentas the specification proceeds, my invention will be best understood by reference tothe following specicat'ion and claims and the illustrations in the accompanying drawingin which: I y

Figure 1 is a vertical section (through a mercury tube with its attendant circuit;

. Figure 2 is a partial section through the lower sulating disc 4 which has a concave upper surface 6 and a central openings therethrough in which is supported one end o1' an electrode I0. This electrode is made of a material having a higher resistance to current flow than mercury and in this instance is formed of carbon. A metal electrode I2 is secured to the carbon and carried by the end of the casing.

Into the side oi the casing 2 there is injected a second electrode I4 which projects into the central aperture for a short distance. There is also provided a third metallic electrode I6 which projects down from the upper end of the casing a considerable distance within the central 'aperture. Secured to this upper electrode is a large cylindrical member I8 formed of electrical insulating material which surrounds and entirely encloses the lower projecting end of the electrode I6 but allows a small portion of the electrode adjacent its support in the casing-.to be exposed as shown at 20. This portion 20 has within a crater 2| in the top of the cylindrical member I8.- Within the casing there is a substantial amount of mercury 22 which entirely covers the two lower electrodes and extends up around the lower end of the cylindrical member I8. Y

A conductive line 24 is connected to electrode I4 and also to one terminal of a battery V26 and to one side of the -secondary 28 ofv a transformer. The electrode I6 is connected by line 30 to the opposite side of the secondary 28 and connected directly across the secondary 28 is a condenser 32. The opposite terminal of the battery 26 is connected to the primary 34 oi' the transformer, the opposite side of which is connected-by line 36 to the electrode I2.'

with the upper surface of the carbon electrode portion of the tube illustrating its action; and

ing, there is shown in Figure 1 an elongated hol-`l low casing 2 `formed of insulating material. In

the lower end of the casing is secured an in- I0 in sufilcient quantity to cause a vaporization A of the` mercury at that point. This vaporiza tion will be sumcient to entirely isolate the liquid mercury from the electrode and thus break the conductive circuit 4which is best shown in detail in Figure 2. As soon, however, as this happens.

current ceases to iiow in this circuit, and the source of heat thus being removed, the vapor will condense and the circuit will .again'be reformed. This operation will continue as long as current is supplied to the system. I have thus provided an automatic interrupter which will provide a series of pulsating currents.

Since this current also flows through the pri-l mary '343 of the transformer, each time current is started and stopped 'there will be induced in the secondary 28 a higher voltage which is applied to the upper electrode it which will then tend to cause an arc between it and the mercury pool. rIhis arc of course is a mercury arc and is carried by the mercury vapor adjacent the upper surface of the pool and this is the source ofultraviolet rays.

I have found, however, thatif the electrode I6 is merely allowed'to project downwardly to ward the mercury pool, the arc `termed, which is the source of some ultraviolet rays, is not a's satisfactory as' might be desired. Therefore; I have applied to the extending end of thevelectrode i6 a long cylindrical member iii formed of electrical insulating material and projects down into the mercury bath, causing the same to rise up around the sides of the same and between it and the casing. 'Ihis causes the arc to occur at various places aroundv the circumference which gives the effect of spreading.v

.transparent casing V2 to cut down the. light transmitted therethrough. I have therefore produced a more efcient, simpler, and long lived y source of ultraviolet rays.

I claim:

1. In a light source, a casing, a pair of electrodes supported in spaced relation by the cas= ing, one of said electrodes being in a liquid state and means formed of insulating material mounted upon and encasing a portion of the other electrode -and projecting down into'the liquid electrode for a substantial distance, thus forcing the liquid up around it.

2. In a light source, a casing formed of transparent electrical insulating material, an electrode supported in one end of the casing, a pool of mercury within the casing, means to apply a potential difference to the mercury and the electrode of such proportions as to cause an arc to be set up and insulating means mounted upon the projecting vend of the upper electrode and encasing a portion thereof and extending down into the mercury a substantial distance causing the mercury to rise up around it whereby the arc will be spread out and cause to migrate around the insulating means.

3. In a light source, a casing formed of transparent electrical insulating material, `an electrode Isupported in one end thereof, a pool of mercury within the casing, means'to apply a potential difference to the mercury and the electrodeof such proportions as to cause an arc to be created, a protective member of insulating material supported on and encasing a portion of said upper electrode and extending down into the mercury for a substantial distance, said member being roughly circular in. cross section thereby causing the mercury to rise in a ring around it and cause the arc to be generated between this ring and the upper exposed portion of the. electrode, whereby the arc will be spread out and caused to migrate.

4. In a light source, a casing formed of transparent electrical insulating material, an electrode supported in one end thereof, a pool of mercury within the casing and spaced from the electrode, means for applying a potential diierence to the mercury and the electrode of sufficient proportions to cause an arc to be formed, an insulating member of the same general configuration as the casing but of smaller cross section so that it will fit within the casing and extend 4down. into the mercury, forcing thelatter up around the sides, carried by and encasing the lower end ofthe upper electrode whereby the arc is developed between the area of mercury between the casing and the central member and the upper electrode to provide an arc which is spread out.

5. In a light source, a cylindrical casing of transparent electrical insulating material, a plurality of electrodes carried by and4 projecting to points within the casing, at least one of which is formed of a material of substantial resistance, a pool of mercury within the casing andextending between two of the electrodes and' a member of insulating material carried by another electrode and partially `encasing the same and eX- tendingdown int-o the mercury, thereby providing a substantially cylindrical path for an arc from the upper mercury surface to the lexposed part of the last named electrode and means to apply a potential difference to the electrodes to cause such arc to be drawn.

6. In a light source, a cylindrical casing formed of transparent insulating material, a plurality of electrodes carried in spaced relation by the casing, a pool ofmercury withinthe casing and interconnecting at least two of the electrodes, a

cylindrical insulating member of smaller diaml eter than the inner diameter of the casing carried by a third electrode, ,encasing a portion thereof and extending into the mercury pool to 'force the mercury up into the space between this member and the casing, and means for applying a potential dierence to all of the electrodes whereby an arc will be generated between the mercuryr surface and the exposed portion -of the f last mentioned electrode.

7. In a light source, a cylindrical casing formedv tablished, a transformer 'coil in this circuit, a

second circuit connected to a third electrode and the source, a transformer-secondary coil cooperating with the rst coil connected in the second circuit whereby higher voltage is induced in the second circuit and applied to the third electrode to draw an arc between it and the mercury pooland insulating means encasing a portion of the third electrode and extending down into the mercury pool to expand the arc.

8. In a light source, a casing formed of transparent electrical insulating material, an electrode isrupported'in one end of the casingga pool of mercury within the casing, means to apply a potential dierence to the mercury and the electrode4 of such proportions as to cause an arc to be set up between the two, a cup-shaped insulating member mounted on the electrode end to shield the same and extend upon between the electrode and the sides of the casing to cause the arc to be formed up over the top of the member and prevent any metal particles from the electrode from splashngnn the inner surface of the casing to darken the same but to catch them on the inner cup surface.

9. In a light source, a casing formed of transparent electrical insulating material, an electrode supported in one end of the casing, a pool of mercury Within the casing, means to apply a po- -tentiai difference to the mercury and the elec trode of such proportions as to cause an arc to be set up between the two, a cup-shaped insulating member mounted on the projecting'electrode end and extending down into the mercury to force the same up around the sides thereof and extend up between the electrode'and the tsides of `the casing to cause the arc to be formed over the top of the member to the upper mercury surface and prevent any splatter to the inner casing 'surface from the electrode to cause discoloration of the same. y

WILLIAM S. BRIAN.

Y CERTIFICATE oF coRREcTIoN. Patent No, 2,289,625. Ju1y-1lh-191i2.

-wIYLLIAM s'. BRIAN.

It sghereby certified that error` appears in the printed specification ofthe above numbered patent requiring correction as follows: Page 5, first column, line b., claim 8, for "upon" read up; and that the said Letters Patent should be read with this correction `therein that the same may oo nform tol therecord of the case in the Patent Office.

Signed and sealed this 1st day of September, D. 1914.2

Henry Van rs'dale, n (Seal) Acting Commissioner of Patents.

CERTIFICATE oF CORRECTION. Patent No, 2,289,625. Ju1y*1h,19b.2.

Y wIILIAM s. BRIAN.

It lehereby cerf-1.'.fc1edA that error appears in the printed sfaecification ofthe above numbered patent requiring correction as follows: Page 5, first column, line lL, claim 8, for "upon" read -up; and that the said Letters Pater-1t should be read with this correction therein that the same may conform` tol the record of the case in the Patent Office.

Signed end sealed this lst day of September, D. 1911.2

v l Henry Van rs'dale, (Seel) Acting Commissioner of Patents. 

